sl_pursuit trajectory

[D. Krasoń]

Hi, Im fairly new to matlab and I'm trying to learn the mechanics of pure pursuit and trajectory planning. In sl_pursuit model I've downloaded the trajectory is a line, not a circle like in the book example. My question is how can I change it to circle or maybe sin function? Also what blocks can I use to create any other x,y referance in myabe  a simpler way than then masked mstraj function used in the example?